UV-vis Absorption Measurements Research Articles

Synthesis and optical properties of ternary TeO2-Bi2O3-Na2O glass system

The glasses with composition TBN: 80TeO2-10Bi2O3-10Na2O in mol% have been prepared by using a conventional melt-quench and pressing technique. Investigation of the prepared sample is done by XRD, EDS and UV–Visible spectroscopy. The glassy nature of prepared sample is confirmed by X-ray diffraction at room temperature and composition is verified by EDS. The density was calculated using the fluid displacement method on the basis of the Archimedes principle. UV–Visible absorption measurements have been taken in the range of 200–1100 nm of TBN glasses having different thickness for the study of optical properties. For the evaluation of optical properties of the samples such as the absorption coefficient (α), cut-off wavelength, forbidden energy band gap (Eopt), refractive index and Urbach Energy (Eu) have been done. The effect of thickness on optical properties is observed.

Synthetic Routes for Heteroatom‐Containing Alkylated/Arylated Polycyclic Aromatic Hydrocarbons

Synthetic routes for heteroatom-containing polycyclic aromatic hydrocarbons (H-PAHs) with alkyl and aryl substitution are demonstrated. Three H-PAHs, including heteroatom-containing rubicenes (H-rubicenes), angular-benzothiophenes (ABTs), and indenothiophene (IDTs) were successfully synthesized by two key steps, including polysubstituted olefin formation and cyclization. Specifically, ABT and H-rubicenes were comprehensively investigated by single-crystal X-ray diffraction, NMR spectroscopy, UV-vis absorption, cyclic voltammetry, transient absorption, and single-crystal OFET measurements.

The influence of Mn doping on the structural and optical properties of ZnO nanostructures

We report the hydrothermal synthesis of Zn1-xMnxO (x = 0.00, 0.02, 0.04, 0.06) nanostructures and their structural, morphological and optical properties. The X-ray diffraction analysis confirmed the wurtzite phase and successful incorporation of Mn in ZnO matrix. Field emission scanning electron microscopy (FE-SEM) images revealed the suppression of growth rate and change in morphology of ZnO from nanoplates to nanorods at higher Mn concentration. Furthermore, a red shift is observed in the Fourier transform infra-red (FTIR) spectra, which is attributed to the variation of bond length and Zn–O–Zn structural perturbation. UV–visible absorption measurements indicated a blue shift in the bandgap from 3.28 eV (pure ZnO) to 3.42 eV (x = 0.06), which is assigned to the Burstein-Moss effect. The photoluminescence spectra exhibited UV excitonic and yellow-green defective emissions. The intensity of broad visible emission peak is decreased which is ascribed to the surface defect quenching due to the presence of Mn as a dopant.

Synthesis and optical properties of copper oxide nanoparticles: effect of solvents

Nanocrystalline copper oxide (CuO) powder was synthesized through solid-state co-precipitation technique using copper sulfate pentahydrate and sodium hydroxide pellets as a source materials. Crystalline nature and surface morphology of the sample are studied through x-ray diffraction, field emission scanning electron microscopy, energy dispersive x-ray, and Fourier transform infrared spectroscopy. Optical properties of synthesized CuO nanopowder were investigated by UV–Vis absorption and photoluminescence spectroscopy. X-ray diffraction study reveals that CuO nanoparticles are in monoclinic structure and crystalline size is found to be around 15 nm as estimated from Debye-Scherrer formula. FESEM measurement confirms that the particles are in almost irregular shape, and some nanorod-like structures are noticed. FTIR spectrum confirms the formation of high-quality and pure CuO nanoparticles. The effect of various solvents on optical properties of CuO nanoparticles is studied. From UV–Vis absorption measurement, a strong quantization along with varying band edges in different solvents was observed. It is seen from photoluminescence spectra that the intensity of emission as well as emission peak wavelength changes with solvents.

Multilayer ZnO/Pb/G thin film based extended gate field effect transistor for low dose gamma irradiation detection

This study demonstrates the shifts in the threshold voltage ((ΔVTH) of a fabricated extended gate field effect transistor (EGFET) induced by low-dose gamma irradiation as a detection procedure for the collective irradiation dose detection. A metal oxide semiconductor field effect transistor (MOSFET) under ionizing irradiation generates electron–hole (e−-h+) pairs within the oxide layer. These massive holes confined inside the oxide layer owing to their low mobility and produce excess charge. Consequently, the characteristics of the MOSFET and VTH (turn on) are altered, which is detrimental to the transistor’s operation unless inhibited. To resolve this issue, chemical bath deposition was used to grow a multilayer ZnO/Pb/G thin film to assess the feasibility of achieving a low dose gamma (Co-60) irradiation detector. The morphology and structure of the as-prepared film were analyzed using FESEM, XRD, and UV–Vis absorption measurements. The irradiation dose-dependent VTHtraits of the ZnO/Pb/G film-based EGFET were found to be linear. Further, it is established that the simple, rapid, low-cost and eco-friendly technique for the extended gate fabrication may constitute a basis for the development of low doses (up to 12.98 μSv) gamma irradiation dosimetry.

Reactions of Medicinal Gold(III) Compounds With Proteins and Peptides Explored by Electrospray Ionization Mass Spectrometry and Complementary Biophysical Methods.

Electrospray ionization mass spectrometry (ESI MS) is a powerful investigative tool to analyze the reactions of metallodrugs with proteins and peptides and characterize the resulting adducts. Here, we have applied this type of approach to four experimental anticancer gold(III) compounds for which extensive biological and mechanistic data had previously been gathered, namely, Auoxo6, Au2phen, AuL12, and Aubipyc. These gold(III) compounds were reacted with two representative proteins, i.e., human serum albumin (HSA) and human carbonic anhydrase I (hCA I), and with the C-terminal dodecapeptide of thioredoxin reductase. ESI MS analysis allowed us to elucidate the nature of the resulting metal–protein adducts from which the main features of the occurring metallodrug–protein reactions can be inferred. In selected cases, MS data were integrated and supported by independent 1HNMR and UV–Vis absorption measurements to gain an overall description of the occurring processes. From data analysis, it emerges that most of the investigated gold(III) complexes, endowed with an appreciable oxidizing character, undergo quite facile reduction to gold(I); the resulting gold(I) species tightly associate with the above proteins/peptides with a remarkable selectivity for free cysteine residues. In contrast, in the case of the less-oxidizing Aubipyc complex, the gold(III) oxidation state is conserved, and a gold(III) fragment still containing the original ligand is found to be associated with the target proteins. It is notable that the C-terminal dodecapeptide of thioredoxin reductase containing the characteristic –Gly–Cys–Sec–Gly metal-binding motif is able in all cases to trigger gold(III)-to-gold(I) reduction. Our investigation allowed us to identify in detail the nature of the gold fragments that ultimately bind the protein targets and determine the exact binding stoichiometry; some insight on the reaction kinetics was also gained. Notably, a few clear correlations could be established between the structure of the metal complexes and the nature of the resulting protein adducts. The mechanistic implications of these findings are analyzed and thoroughly discussed. Overall, the present results set the stage to better understand the real target biomolecules of these gold compounds and elucidate at the atomic level their interaction modes with proteins and peptides.

Novel homogeneous catalyst assisted sonocatalytic degradation of dye Direct Blue 71

Industrial effluents, particularly from dye industry, is one of the major causes of serious concern as it contaminates the environmental water resources and affect human health. Treatment of such contaminants is a challenging area of interest to researchers. In this context, here, we have explored degradation and mineralization of Direct Blue (DB71) dye in aqueous solution by means of ultrasound irradiation at a frequency of 25 kHz and its combination with a novel homogenous sonocatalyst is investigated. The following experiments have been conducted to achieve complete degradation of the dye molecule. In-situ generation of the radicals under ultrasonic irradiation is measured by EPR technique. The effects of various operational parameters such as the effects of pH, dye concentration, catalyst dosage, electrolytes, energy input and kinetics of oxidation processes on the degradation efficiency are studied. COD measurements are also carried out in order to evaluate the mineralization efficiency of DB71. The effect of electrolytes on dye degradation is studied with different inorganic electrolytes. The rate constant decreases with increasing dye concentration. The degradation increases with increasing catalyst concentration and decreases with increasing dye concentration. Sonocatalytic degradation of the dye molecules are observed by UV-visible absorption and TOC measurements. The by-products formation of the sonocalytically degraded dye samples are analyzed by ESI-MS+ analysis. The catalyst is also tested for its efficiency in the degradation of real dye house effluents.

High resolution structural refinement and band gap characterization of the defect chalcopyrites CuIn5Te8, AgIn5Te8 and AuIn5Te8

The AIn5Te8 compounds (A ​= ​Cu, Ag, Au), charge balanced defect chalcopyrites, are characterized. Synchrotron powder diffraction shows that the Cu and Ag analogs are tetragonal to high precision at room temperature, with classic 158 (I-III5-VI8) defect chalcopyrite structures in space group I4¯2m. These materials display ordered vacancies but disordered cations. The degree of cation intermixing is more significant in the Cu case than in the Ag case. In contrast, AuIn5Te8, a previously unreported 158 defect chalcopyrite, exhibits a tetragonal P4¯2c structure with disordered vacancies and cations, displaying poorer crystallinity than the other two materials. The direct optical band gaps (Eg), determined from UV–vis absorption measurements, are estimated to be 0.94, 0.99, and 0.77 ​eV, respectively. Comparison to the corresponding sulfides and selenides for 158 and standard 112 (I-III-VI2) type chalcopyrites is reported where the data are available.

Revealing the optical properties of polycyclic aromatic hydrocarbon clusters with surface formyl groups

Soot particles from flames were found to have quantum confinement behavior in recent UV–visible absorption measurements. However, the impact of surface functionalization was not considered in the previous interpretation. In this work, polycyclic aromatic hydrocarbon (PAH) clusters was selected as a model system of soot to explore the impact of surface functionalization on the optical properties. The HOMO–LUMO gap of PAH clusters with formyl group (–CHO) substitutions was computed using the B3LYP method with the 6-31G(d) basis set. The results showed that the HOMO–LUMO gaps of PAH clusters strongly depend on the surface coverage of –CHO groups on particle, and a higher coverage always yield a reduced gap value. Combining the observation from X-ray photoelectron spectroscopy measurements, the impact of functional groups was computed as 0.27–0.71 eV. Detailed analysis on the electronic structures of HOMO and LUMO reveals that the –CHO groups lower the LUMO energy to a great extent, while they have limited impact on the HOMO energy. Furthermore, we use the LUMO composition as a key descriptor to evaluate the impact of functionalization on LUMO energy, and a theoretical limit of gap reduction was calculated as 1.1 eV for both pyrene and coronene clusters.

Influence of Incorporated Barium Ion on the Physio-Chemical Properties of Zinc Oxide Nanodisks Synthesized via a Sonochemical Process.

Nanostructure materials are of interest in last few decades due to their unique size-dependent physio-chemical properties. In this paper, zinc oxide (ZnO) and barium doped ZnO nanodisks (NDs) were synthesized using sonochemical method and characterized by various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), UV-vis absorption and dielectric measurements. The XRD and FTIR studies confirm the crystalline nature of ZnO NDs, and the average crystallite size was found to be ~25 nm for pure ZnO and ~22 nm for Ba doped ZnO NDs. SEM study confirmed the spherical shaped ZnO NDs with average sizes in the range of 20-30 nm. The maximum absorbance was obtained in the 200-500 nm regions with a prominent peak absorbance were observed by UV-vis spectra. The corresponding band gap for ZnO NDs and Ba doped ZnO NDs were calculated using Tauc's plot and was found to be 3.12 and 3.04, respectively. The conductivity and dielectric measurements as a function of frequency have been studied.

A study of the structure, luminescence and cytotoxicity of new green-emitting terbium-doped CaS nanophosphors

CaS nanoparticles have attracted significant attention due to their wide range of optoelectronic applications. The synthesis of CaS nanophosphors doped with different terbium concentrations through a simple wet chemical co-precipitation method using triethanolamine (TEOA) as a capping agent is reported here. X-ray diffractogram ensured that the nanoparticles were crystallized in the cubic phase with space group $$Fm\overline{3}m$$ . Morphology and particle size of the TEOA-capped CaS:Tb nanophosphors were determined using scanning electron microscopy and transmission electron microscopy. The optical properties of the samples were studied by photoluminescence spectroscopy and UV–Vis absorption measurements. The prepared nanoparticles exhibited green luminescence, which is attributed to 5D4–7FJ transitions of terbium ions incorporated into the CaS lattice. The existence of various functional groups in the synthesized products was identified by Fourier transform infrared spectroscopy. The lifetime decay measurements showed that the lifetime of the samples was in the nanosecond range. Cytotoxicity analysis of the nanoparticles was carried out on L929 fibroblast cells, which confirmed that the nanoparticles are biocompatible across a wide range of concentrations. Our findings indicate that CaS:Tb nanophosphor could be a potential candidate as a green-emitting phosphor in optoelectronics and biomedical field.

Synthesis of Nano ZnO: A Catalyst for N-formylation of Aromatic Amines and Biodiesel Application

Background: Zinc oxide nanoparticles prepared from an easy, eco-friendly and cost-effective green combustion technique using an extract of turmeric root has been an immense attractive nanomaterial that is used widely in light emitting display systems, piezoeletricity, electric conductivity, and biological applications. The prepared samples were characterized for their structural and morphological study using various analytical techniques. Results: Crystallite size was calculated by both XRD as well as UV-visible absorption measurements and Crystallite size was found to be 14-36 nm. An equation was developed with the aid of an effective mass model (Brus 1986) to calculate the size of the particle as a function of the peak absorbance wavelength. The energy bandgap of the synthesized sample calculated to be in the range of 4.74 - 5.0 eV by UV-Vis spectra confirms the quantum confinement. ZnO nanocatalyst is used for the synthesis of biodiesel from garcinia gummigutta seed oil has been studied. The environmental friendly procedure was carried for the formylation of amines under solvent-free reaction condition and simple work-up giving pure products with prompt recyclability behavior are the main features of the reaction. Conclusion: In this work, ZnO NPs were synthesised using turmeric root extract as a fuel via green combustion method. It is an environmentally friendly, easy as well as cost-effective method for the synthesis of nanoparticles. ZnO NPs were examined through various equipments such as PXRD, UV-Vis, FTIR, and SEM studies. XRD study show the hexagonal wurtzite structure. it is a good catalyst for the synthesis of biodiesel from the pongamiapinnata oil. It also serves as a catalyst for the Nformylation reactions, which involves the clean procedure under milder reaction conditions with an excellent yield of the desired products

Achieving Balanced Crystallization Kinetics of Donor and Acceptor by Sequential‐Blade Coated Double Bulk Heterojunction Organic Solar Cells

AbstractSequential deposition has great potential to achieve high performance in organic solar cells due to the resulting well‐controlled vertical phase separation. In this work, double bulk heterojunction organic solar cells are fabricated by sequential‐blade cast in ambient conditions. Probed by the in situ grazing incidence X‐ray diffraction and in situ UV–vis absorption measurements, the seq‐blade system exhibits a different tendency from each of the binary films during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB‐T:FOIC film displays a strong and large phase separation, resulting in low current density (Jsc) and unsatisfactory power conversion efficiency. In the seq‐blade cast system, the bottom layer PBDB‐T:IT‐M produces many crystal nuclei for the top layer PBDB‐T:FOIC, so the PBDB‐T molecules are able to crystallize easily and quickly. Balanced crystallization kinetics between polymer and small molecule and an ideal percolation network in the film are observed. In addition, the balanced crystallization kinetics are favorable toward realizing lower recombination loss through charge transport processes.

Alternative particle compensation techniques for online water quality monitoring using UV–Vis spectrophotometer

Particles in the water can significantly affect UV–Vis absorption measurements. There is a need for the water industry to develop a reliable technique to eliminate particle impact on on-line water quality monitoring using UV–Vis spectroscopy. This study aims to develop and use digital techniques for particle compensation: single wavelength compensation, linear regression compensation and multiplicative scatter correction method for on-line UV–Vis spectrophotometers. Water quality data were collected from three selected water sources in water treatment plants which represent different water qualities in terms of particles and organic matters. UV254 measurements were determined with these three software compensation techniques in comparison with the proprietary instrument built-in compensation algorithm using Bland-Altman analysis. Linear correction methods were found to be able to adjust the three compensation techniques to achieve acceptable compensated UV254 results, particularly for raw waters. UV254 measurements using single wavelength compensation, linear regression compensation and multiplicative scatter correction techniques with the assistant of linear correction methods were confirmed to be comparable to the instrument built-in compensation method. Our results reveal that these particle compensation techniques can make the UV254 technology reliable for online water quality monitoring in water treatment network. This paper demonstrated the advantage of using software compensation method to establish local compensation and calibration models instead of relying on the predetermined global calibrations for online water quality monitoring.

Rational design of Ag-ZnO-Fe3O4 nanocomposite with promising antimicrobial activity under LED light illumination

Surface plasmon resonance effect, Fenton’s reaction, plant extract, and nanoparticles have all proven to be efficient in killing or reducing the activity of numerous microorganisms. To study the synergetic effects among these key parameters, Ag-ZnO-Fe3O4 nanocomposites have been synthesized via solution combustion approach in the presence of aqueous extract of Thymus vulgaris leaves. The successful construction of Ag-ZnO-Fe3O4 nanocomposite and its purity were confirmed by X-ray diffraction, X-ray photoelectron spectra, and energy dispersive X-Ray spectroscopy analyses. Dynamic light scattering and transmission electron microscopy measurements showed that the size of the obtained particles is in the nanoscale. The synthesized nanocomposite showed broad inhibition against the selected bacteria and yeast under LED light. UV–vis absorption measurement showed that the heterostructure exhibits broad plasmonic peak centered around 434 nm. Hot charge carriers are generated in Ag under LED light illumination and separated through Ag-ZnO heterojunction resulting in the production of a considerable amount of OH radicals as confirmed by ESR analysis. Moreover, Ag acts as H2O2 donator and photogenerated electrons provider for the Fenton’s reaction, resulting in the generation of much more OH radicals. Therefore, Ag-ZnO-Fe3O4 nanocomposite shows improved microbial activity under LED light illumination.

Synthesis, crystal structure, physical and catalytic oxidation studies of a new hybrid phosphate [(N2H5)2Co(HPO4)2

A new one-dimensional coordination polymer [(N2H5)2Co(HPO4)2] was synthesized by slow evaporation method and characterized by means of single-crystal X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Its catalytic activity was tested using UV–visible absorption measurements. The compound crystallizes in the monoclinic system (S.G: P21/c) with the cell parameters (Å, °): a = 5.3665(3), b = 11.1271(6), c = 7.7017(4), β = 104.843(4), V = 444.55(4) Å3 and Z = 2. The crystal structure, consisting of a linear chain, is made of rings of [CoN2O4] octahedra and [PO3(OH)] tetrahedra sharing vertices via oxygen atoms coordinated to cobalt centers. The rings are linked to chains running along [100] and form thereby polymeric chains that are connected by hydrogen bonds in a three-dimensional arrangement. The FTIR spectroscopy shows the expected bands of hydrazine and phosphate groups. The thermal behavior consists mainly of the loss of hydrazine moieties leading thus to the formation of anhydrous cobalt phosphate. The phosphate complex exhibits efficiency in catalytic oxidation and degradation of methylene blue dye. The ac magnetic susceptibility shows a peak indicating antiferromagnetic order with a Néel temperature of 5.5 K. Fitting the Curie-Weiss equation to the ac magnetic susceptibility above 50 K gives the average Curie-Weiss Constant to be −11.8 K.

Fluorescence-enhanced second harmonic normal Raman scattering in β-carotene.

β-carotene, an important biomolecule from the carotenoid family, plays a vital role in biosystem, the characteristic features of electronic and vibrational spectra will shed light on its photophysical properties. Here, in-situ high pressure Raman spectra of β-carotene are measured up to 26GPa. Two possible phase transitions are identified at about 7GPa and 14GPa, respectively, through analysis of the frequency-pressure relationships. In order to clarify the intensity changes of Raman bands, high pressure UV-Vis absorption measurements of β-carotene are conducted. Besides resonance Raman enhancement effect, a new mechanism, fluorescence enhancement of normal Raman scattering, is proposed, which provides new methods and approaches for Raman spectroscopy.

Processing and Study of Optical and Electrical Properties of (Mg, Al) Co-Doped ZnO Thin Films Prepared by RF Magnetron Sputtering for Photovoltaic Application.

In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al2O3 (10:2 wt %) material. The films were deposited on glass and silicon substrates at the different working pressures of 0.21, 0.61, 0.83 and 1 Pa, 300 °C and 250 W of power. X-ray diffraction patterns (XRD), atomic force microscopy (AFM), UV-vis absorption and Hall effect measurements were used to evaluate the structural, optical, morphological and electrical properties of thin films as a function of the working pressure. The optical properties of the films, such as the refractive index, the extinction coefficient and the band gap energy were systematically studied. The optical band gap of thin films was estimated from the calculated absorption coefficient. That parameter, ranged from 3.921 to 3.655 eV, was hardly influenced by the working pressure. On the other hand, the lowest resistivity of 8.8 × 10−2 Ω cm−1 was achieved by the sample deposited at the lowest working pressure of 0.21 Pa. This film exhibited the best optoelectronic properties. All these data revealed that the prepared thin layers would offer a good capability to be used in photovoltaic applications.

Retraction Note to: Synthesis and characterization of Ni-doped α-Fe2O3 nanoparticles through co-precipitation method with enhanced photocatalytic activities

In the present study, an attempt has been made for synthesis, characterization and photocatalytic application of pure and Ni-doped α-Fe2O3 (hematite) nanoparticles by chemical co-precipitation method. The synthesized products have been studied by Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Ultraviolet–Visible (UV–Vis) analysis and Vibrating Sample Magnetometer (VSM). The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. TEM and SEM show that the size of the nanoparticles decreases with Ni-doping. FTIR and Raman spectroscopies confirm the phase purity and the phonon modes of the synthesized nanoparticles. The UV–Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.02 eV for α-Fe2O3 down to 1.81 eV for 8 mol% Ni-doped α-Fe2O3. Furthermore, the magnetic properties demonstrated that all of the samples exhibited ferromagnetic behavior at room temperature. On the other part, the photocatalytic activity of Ni-doped α-Fe2O3 particles was studied using methylene blue (MB) as model organic pollutants. The 8 mol% Ni-doped α-Fe2O3 nanoparticles disclosed that the discoloration of MB reached 86% after irradiation of 140 min.

Direct bio-interface preparation for Spirulina and conductive polymer composite

Emulsion chemical polymerization of phenylacetylene and electrochemical polymerization of pyrrole on Spirulina surface having a micro-helical structure were carried out. A polymerization reaction progressed on the surface of Spirulina that acted as a bio-template. Micro-spectroscopy infrared (IR) absorption and micro-spectroscopy ultra-violet (UV-vis) absorption measurements were carried out to confirm the chemical structures. The surface of the bio-tissue-conducting polymer composite was investigated using optical microscopy and scanning electron microscopy (SEM). The results of the current study demonstrate the deposition of conducting polymers on the surface of micro-organisms in water. This method allows for the preparation of electro-active composites with an ordered structure using the micro-structures of biological tissues as templates.